Thanks to fires in western Montana and Idaho in August 2007, pollutants traveled eastward across much of the United States, affecting air quality hundreds of miles from the flames. According to the U.S. Air Quality (Smog Blog) at the University of Maryland, Baltimore County, air quality along the U.S. East Coast suffered from the northwestern fires.
This image tracks the smoke east from Idaho and Montana across North and South Dakota, Minnesota, Iowa, and Wisconsin by showing carbon monoxide concentrations, one component of the smoke, as observed by the Measurements Of Pollution In The Troposphere (MOPITT) instrument aboard NASAs Terra satellite between 1 August and 20 August 2007. The colors represent the carbon monoxide concentrations in parts per billion by volume at an altitude of approximately 3 kilometers (1.9 miles). Lowest concentrations appear in yellow and highest concentrations appear in red. Black indicates areas where persistent cloud cover prevented thoroughmeasurements.
MOPITT – Terra
1-20 August 2007
An arc of high carbon monoxide levels reaches from central Idaho, through Montana, and dips southward across South Dakota. This area matches smoke plumes that were visible across the area in mid-August. Concentrations remain high as far east as the Great Lakes region. Along the top left edge of the image, patches of dark red across Alberta and Saskatchewan are probably also the result of forest fire activity in August.
Fires produce large amounts of carbon monoxide, which remains in the atmosphere for about two months on average. By contrast, the gray particles that make the smoke visible in the air disappear after about a week. Because carbon monoxide stays in the atmosphere so long, scientists can track a plume of smoke much farther by measuring carbon monoxide than by looking for visible signs of the smoke. Compared to the particles, carbon monoxide also acts more like other gaseous pollutants in the smoke that might be hard to measure directly. As a result, measurements of carbon monoxide provide an estimate of how much of these pollutants were emitted by the fires. In addition to revealing pollution from a single event, the view of carbon monoxide from space gives remote-sensing scientists a way to trace the global transport of smoke-relatedpollution.
Smoke from fires in Idaho and Montana
On 13 August 2007, while docked to the International Space Station (ISS), the crew members of Shuttle Mission STS-118 and ISS Expedition 15 reported seeing the smoke plumes from wide-spread fires across Idaho and Montana. The crew photographed and downlinked images of isolated plumes (top image) and regional views of the smoke (bottom image) from different perspectives. Strong westerly winds were driving the smokeeastward.
The close-up view shows the WH Complex Fire in southern Montana, which was burning in Gallatin National Forest. As ofFriday, 17 August, the National Interagency Fire Center estimated its size as 25,400 acres, and it was only 5 percent contained. The rugged topography that makes firefighting in the area so difficult is highlighted by shadows created by the oblique (from the side) perspective from which the astronauts took the photo. The plume has topography of its own, some plumes towering above others, casting dark shadows.
The regional view was taken looking westward toward the horizon. It shows fires not only in Montana, but also fires to the south in Wyoming, and to the northwest in Idaho. South (to the left) of the WH Complex Fire are the Columbine 1 Fire in Yellowstone National Park (18,500 acres and 0 percent contained), and the Hardscrabble Fire in Bridger-Teton National Forest (3,074 acres and 40 percent contained).
An even broader regional view of the extent of the fires was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard NASAs Aqua satellite on 12 August 2007, the day before these images were taken by astronauts onboard the ISS.